Forest mushrooms, or shiitake (Lentinus edodes), have been used both as food and medicine in Asia for hundreds of years. However, cultivation of shiitake has remained in a primitive state until very recently. Shiitake traditionally have been grown on tree trunks, some types of trees supporting more abundant growth than others. Growth of shiitake on trees typically requires between one and two years until the first crop of fruiting bodies is produced.
One method which has been found to expedite the growth of shiitake involves growing the mushrooms aseptically in plastic bags or in trays on sterilized substrate. Such substrates generally include saw dust, bagasse, straw, paper chips and the like, which are supplemented with nutrients such as starch, yeast, sugars and protein. Using this method, mushrooms can be harvested in as little as three to four months after inoculation.
Unfortunately, this aseptic growth method is ill suited to the established equipment and procedures employed by large scale, commercial growers of white mushrooms (Agaricus). White mushrooms are grown on a pasteurized, composted substrate in trays. Therefore, there is a need for a method of growing shiitake mushrooms which is compatible with the techniques and apparatus used by the industry.
The basic procedure for commercially growing mushrooms involves either bulk pasteurization of compost in highly insulated rooms called "tunnels," or pasteurization of compost in trays. Such compost is then impregnated with mushroom mycelia. This step is referred to as "spawning", and is generally performed in individual beds or trays to facilitate handling and to maximize space utilization. Alternatively, the spawning can be performed in bulk. The spawn-impregnated compost is then allowed to develop under controlled temperature and moisture conditions. When the compost is spawned in bulk, the trays are filled after the spawn has permeated the compost. Once the hyphae of the mushrooms have permeated the compost, conditions are altered to cause the mushrooms to fruit. In the case of white mushrooms, a thin layer of soil, sand or peat is placed on top of the bed. The process of covering the bed is referred to as "casing". In the case of shitake, fruiting is stimulated by significantly reducing the temperature of the mushroom beds. After the first crop of fruit has been harvested, additional cycles of fruiting occur, referred to as "breaks" or "flushes", until the nutrients in the compost have been depleted.
It is an object of the invention to provide a substrate for growing shiitake mushrooms.
It is another object to provide a substrate for growing shiitake mushrooms which is compatible with the apparatus and techniques used by commercial mushroom growers.
It is yet another object to provide a substrate for growing shiitake mushrooms which allows a first harvest within two to four months of spawning.
It is still another object of the invention to provide a method for growing mushrooms which eliminates the need for aseptic growth conditions.